Sciencemadness Discussion Board

Cu + H2SO4 + heat = black precipitate & a Sulfur oxide(s) - where is the CuSO4?

RogueRose - 31-1-2017 at 20:10

I tried adding small clippings of wire (10gr of 18-20ga & 2-3mm length) to 93% H2SO4 as well as 31% then heated. When heated to boiling the concentrated turned black pretty quickly and emitted a strong sulfur gas whether it is dioxide or triodixe or both, IDK, but it looks like CuO was produced very efficiently. The diluted acid acquired a grey tint although remains clear.

I've seen a lot of videos where this reaction creates CuSO4 and know that this works when adding H2O2.

Does the Cu act as a catalyst that breaks down the acid. Wiki states that CuSO4 is made industrially by heating the Cu or Cu oxides in hot concentrated acid. Was too much heat used maybe, that doesn't allow the formation of the sulfate?

DraconicAcid - 31-1-2017 at 20:51

I suspect you'll get CuSO4 in more dilute acid, or under less-than-boiling conditions.

Amos - 1-2-2017 at 12:20

Use dilute acid, closer to 10-20%, and use a wide shallow container so it can take up plenty of oxygen to serve as your oxidizing agent.